1. Technical Field
The invention relates to the field of electronic devices having microchannel plates (“MCPs”), and more particularly to methods of bonding a microchannel plate (“MCP”) to other components.
2. Background Art
The present invention describes methods of bonding electro-optical components to a feed-through. The methods described herein may include bonding of other electrical, optical and mechanical components where:    (1) mechanical hold downs or retainers are not desired;    (2) morphology of the two bonding materials is not adequate for a direct surface to surface bond;    (3) bonding involves brittle materials with low shear strength;    (4) a bonding process that does not require solders or braise joints;    (5) a bonding process that does not require melting of the bonding material;    (6) mechanical and electrical bonds are desired on the same interface;    (7) the bonding must provide both electrical and mechanical interconnects; or,    (8) creation of the bond does not permanently alter the components being bonded.Prior Methods
Method 1: Kovar rings brazed to ceramics to facilitate compressing the micro-channel plate (“MCP”). This method requires contacting both sides of the micro-channel plate to facilitate both the electrical and mechanical interconnects, and this is the primary disadvantage compared to this invention. The upper ring would serve as the upper electro-mechanical inter-connect, and the lower ring would serve as the lower electro-mechanical interconnect. This method has been used for decades to manufacture image intensifier devices.
Method 2: An alternative method is described in U.S. Pat. No. 6,040,657 that uses solder or brazing materials of Indium, Indium tin Alloys, Gold-Tin alloys and Gold-Germanium alloys, etc. to flow and wet the micro-channel plate to the feed-through assembly. A primary disadvantage to Method 1 is that a large perimeter portion of the micro-channel plate is covered by a retainer ring used to hold the micro-channel plate in position. The retainer ring occupies space in the ceramic feed-through and also requires complimentary rings to hold and position the retainer; in all there are at least 4 additional rings in the feed-through required for this Method. Additionally the perimeter coverage of the micro-channel plate restricts the design of the cathode input window, because it must accommodate the added height of the retainer and complimentary supports.
Added costs are incurred by Method 1 due to the additional supports and inherent yield losses due to assembly.
A primary disadvantage to Method 2 is that the micro-channel plate must be coated with a metal electrode suitable for bonding with the alloy material. Patterning the electrode to provide electrical and mechanical interconnects to the micro-channel plate becomes very difficult because the flow of the molten alloy material is uncontrolled. The uncontrolled flow of the alloy may allow contact with the micro-channels, which is undesirable for proper operation. The primary advantage of the current invention is that there is no flow of material.
Method 2 eliminates only 1 of the support rings so there are still 3 additional pieces required over the present invention.
U.S. Pat. Nos. 5,514,928 and 5,632,436 disclose “interbonding” two or more micro-channel plates using an alloy similar to those described in Method 2 above. These patents do not discuss bonding of a micro-channel plate to a ceramic feed-through.
U.S. Pat. No. 6,040,657 teaches a “solder pin” to conductively contact the micro-channel plate as described in Method 2 above.
U.S. Pat. No. 5,994,824 discloses a “metallized snap ring” similar to that used in Method 1 above.
U.S. Pat. No. 5,573,173 teaches “diffusion bonding,” but describes use with an electron gun and a cathode ray tube.
While the above cited references introduce and disclose a number of noteworthy advances and technological improvements within the art, none completely fulfills the specific objectives achieved by this invention.